The Boulder Valley School District is continuing to struggle with eradicating a persistent sewer gas smell at Boulder's rebuilt Casey Middle School, though efforts have helped.

Parents and teachers at the school, rebuilt in 2009-10 for $33 million, have complained about an intermittent stink of rotten eggs over the last few years, with at least one parent expressing concern that it was causing a child to feel sick over a few days.

"We know the odor and presence of the gas is of a significant concern to the people in the building," said Boulder Valley spokeswoman Susan Cousins. "We're committed to finding a solution to this."

Air quality testing found low levels of hydrogen sulfide, with levels well below what's considered harmful or a nuisance, using the most conservative measures, according to a review by Boulder County Public Health.

"I know of nothing at the levels they've been measuring that would cause a problem," said Michael Richen, an industrial hygienist with Boulder County Public Health. "I would be comfortable with my kids there."

Still, he said, he doesn't discount that students and staff members who are more sensitive to smells could still occasionally smell the gas or could find the smell makes them a bit nauseous.

District officials blame the stinky odor on minor issues with the HVAC and plumbing systems.

Advertisement

Boulder Valley staff members have worked with environmental and design professionals to identify and mitigate the source of the gas, trying various fixes, district officials said. But while the odors became fainter after each fix, they kept coming back, especially in cold weather or during major changes in air pressure that are common in the spring.

The first fix was to the school's "p-traps," which weren't functioning correctly. A p-trap is a piece of plumbing pipe shaped like a "P" that prevents sewer gases from escaping back into a building.

After more complaints this spring term, the district contracted with Quest to conduct air quality tests in three locations in March. Those tests found very low levels of the gas, below published nuisance thresholds.

On the advice of a mechanical engineer, the district then conducted a pressurized smoke test of the entire plumbing system over spring break, finding four leaks in the system. Those leaks were repaired. Two vents outside third-floor classrooms also were replaced with one-way vents that don't allow sewer gases to escape and waft in through open windows.

A second smoke test after the repairs showed no issues, district officials said.

But a second round of air quality tests earlier this month found the same average concentrations of hydrogen sulfide in all three areas tested — two classrooms and a copy room — though maximum concentrations were lower than in March and all were below published odor and nuisance thresholds.

Next steps include consulting with a mechanical engineer from the company that designed the building and potentially contracting with an independent mechanical engineer to provide another opinion. The district also plans to continue to fine-tune the building's ventilation system.

Richen, of the health department, said his best guess is that the lingering smell is caused by the building being designed as a slightly negative-pressure environment, versus a positive-pressure environment that prevents drafting in vents.

"Until the negative-pressure issue is addressed, they may continue to have problems," he said. "It's just a tough situation. It seems like an awful tough nut to crack."

For more information, including the results of the air testing, go to bvsd.org.

Local duo joining overseas exhibition excursionFilippo Swartz went to Italy, where his mother was born and he spent the first year or so of his life, every summer until he had to stick around to be a part of summer football activities for the Longmont High School team. Full Story

MacIntyre says the completed project will be best in Pac-12There were bulldozers, hard hats, mud, concrete trucks, blueprints, mud, cranes, lots of noise and, uh, mud, during the last recruiting cycle when Colorado football coach Mike MacIntyre brought recruits to campus. Full Story

Most people don't play guitar like Grayson Erhard does. That's because most people can't play guitar like he does. The guitarist for Fort Collins' Aspen Hourglass often uses a difficult two-hands-on-the-fretboard technique that Eddie Van Halen first popularized but which players such as Erhard have developed beyond pop-rock vulgarity.
Full Story